JP2018073600A - LED lamp - Google Patents

Abstract

An LED lamp for DC input capable of preventing a failure or shortening of the life of an LED array even when an incompatible AC power supply is connected.
An LED lamp for DC input includes a full-wave rectifier circuit for full-wave rectification of an input voltage Vin, a series circuit of an LED array and a switch element to which an output voltage of the full-wave rectifier circuit is applied. A voltage detection circuit 40 that divides and rectifies the input voltage Vin and outputs a detection voltage Vd, and maintains the switch element 31 in the OFF state when it is determined that the detection voltage Vd is a rectified waveform of an AC voltage. And a control circuit 50 configured as described above.
[Selection] Figure 1

Description

  The present invention relates to an LED lamp, and more particularly to an LED lamp for DC input constituting a polarity-free light bulb.

  Patent Document 1 discloses an AC LED lighting circuit in which an LED is connected to an AC power source via a rectifier. In this AC LED lighting circuit, a plurality of LEDs are connected in series, and a fluorescent lamp ballast is connected in series between the AC power source and the rectifier. The number of installed LEDs is adjusted so as to correspond to the lighting voltage of the lamp suitable for the lamp ballast.

JP 2009-238579 A

  By the way, the LED lamp constituting the so-called polarity-free light bulb is lit in the same way regardless of the polarity of the LED power source, which is a DC power source, as well as the above AC input LED lamp. There is also an LED lamp for direct current input configured as described above. Even in such an LED lamp for DC input, when an AC power supply such as a magnetic ballast is mistakenly connected, a pulsating voltage obtained by full-wave rectification of the AC voltage from the AC power supply is applied to the LED array. The When the peak value of this pulsating voltage exceeds the forward voltage of the LED array, the LED array repeatedly turns off at the valley of the pulsating voltage and turns on at the peak, and thus has a frequency twice that of the power supply frequency (ie , 100 Hz or 120 Hz). Here, when the peak value of the pulsating voltage exceeds an appropriate forward voltage of the LED array, the LED array is in an overvoltage state (and therefore an overcurrent state) in lighting at the peak portion. However, since intermittent lighting at the above frequency appears to be continuous lighting to the user's eyes, the user may continue to use it without recognizing the connection of an incompatible AC power supply that causes an overvoltage condition of the LED array. There is sex. Continued lighting in such an overvoltage state causes a failure or a shortened life of the LED array.

  Therefore, an object of the present invention is to provide an LED lamp for DC input capable of preventing a failure or shortening of the life of an LED array even when an incompatible AC power supply device is connected.

  The LED lamp for DC input according to the first to third embodiments of the present disclosure includes a full-wave rectifier circuit that full-wave rectifies an input voltage, and an LED array and a switch element to which an output voltage of the full-wave rectifier circuit is applied. A series circuit, a voltage detection circuit that divides and rectifies the input voltage and outputs a detection voltage, and is configured to maintain the switch element in an off state when it is determined that the detection voltage is a rectified waveform of an AC voltage. And a control circuit.

  According to the above configuration, when the input voltage is an AC voltage, the switch element is turned off, and the current path between the full-wave rectifier circuit and the LED array is opened. Therefore, the overvoltage from the incompatible AC power supply device to the LED array can be reduced. Application is stopped. Therefore, even when an incompatible AC power supply device is connected, a LED lamp for DC input capable of preventing a failure or shortening of the life of the LED array is realized.

  In the LED lamp of the first form, the voltage detection circuit is composed of a voltage dividing rectifier circuit that divides the input voltage by a predetermined voltage dividing ratio and rectifies the wave in full and outputs the detected voltage, and in order of giving the rated current to the LED array. A threshold value less than the lower limit value of the voltage range obtained by multiplying the directional voltage range by the voltage division ratio is defined, and the control circuit is configured to maintain the switch element in the OFF state when detecting a waveform portion where the detected voltage is equal to or lower than the threshold value. Is done. Thereby, a low-cost LED lamp using a control circuit having a simple processing configuration is realized.

  In the LED lamp according to the alternative example of the first embodiment, the voltage detection circuit includes a voltage dividing rectifier circuit that divides the input voltage at a predetermined voltage dividing ratio and rectifies the half wave to output the detection voltage. A predetermined voltage range that is less than the lower limit value of the voltage range obtained by multiplying the forward voltage range by the voltage division ratio and higher than zero is defined, and the control circuit switches the switch element when the detected voltage is detected within the predetermined voltage range. Configured to remain off. Thereby, a low-cost LED lamp using a voltage detection circuit having a simple half-wave rectification configuration is realized.

  In the LED lamp of the second form, the voltage detection circuit is composed of a voltage dividing rectifier circuit that divides the input voltage at a predetermined voltage dividing ratio and outputs the detected voltage by full-wave rectification or half-wave rectification, and is rated for the LED array. A threshold value that is equal to or higher than the upper limit value of the voltage range obtained by multiplying the forward voltage range that provides current by the voltage division ratio is defined, and the control circuit maintains the switch element in the OFF state when a waveform portion in which the detected voltage exceeds the threshold value is detected. Configured as follows. Thereby, a low-cost LED lamp using a control circuit having a simple processing configuration is realized.

  The LED lamp of the third form further includes a warning LED and a transistor connected in series to a predetermined voltage source in the LED lamp of the first or second form, and the control circuit sets the switch element to an on state. When the switch is turned off, the warning LED is turned off, and when the switch element is turned off, the transistor is turned on and the warning LED is turned on. As a result, it is possible to make the user recognize by turning on the warning LED that the turning off of the LED array is caused by the connection of an incompatible AC power supply device, and it is possible to prompt the correct use of the LED lamp. Become.

  The LED lamp for DC input of the fourth form includes a full-wave rectifier circuit that full-wave rectifies an input voltage, a series circuit of an LED array and a switch element to which an output voltage of the full-wave rectifier circuit is applied, and an input voltage A voltage detection circuit that divides the voltage by a predetermined voltage division ratio and outputs a detection voltage by full-wave rectification, and an upper limit value of the voltage range obtained by multiplying the forward voltage range that gives the rated current to the LED array by the voltage division ratio, And a control circuit configured to turn off the switch element during a period in which the detected voltage exceeds the upper limit value.

  According to the above configuration, when the input voltage is a high peak AC voltage, the switch element is turned off near the peak, and the current path between the full-wave rectifier circuit and the LED array is opened. Application of overvoltage from the device to the LED array is prevented. Therefore, even when an incompatible AC power supply device is connected, a LED lamp for DC input capable of preventing a failure or shortening of the life of the LED array is realized.

It is a circuit diagram of the LED lamp of 1st, 2nd and 4th embodiment. It is a figure explaining operation | movement of the LED lamp of 1st Embodiment. It is a figure explaining operation | movement of the LED lamp of 1st Embodiment. It is a figure explaining operation | movement of the LED lamp of 1st Embodiment. It is a circuit diagram of the LED lamp of the modification of 1st and 2nd embodiment. It is a figure explaining operation | movement of the LED lamp of the modification of 1st Embodiment. It is a figure explaining operation | movement of the LED lamp of the modification of 1st Embodiment. It is a figure explaining operation | movement of the LED lamp of the modification of 1st Embodiment. It is a figure explaining operation | movement of the LED lamp of 2nd Embodiment. It is a figure explaining operation | movement of the LED lamp of 2nd Embodiment. It is a circuit diagram of the LED lamp of 3rd Embodiment. It is a figure explaining operation | movement of the LED lamp of 4th Embodiment. It is a figure explaining operation | movement of the LED lamp of 4th Embodiment.

<First Embodiment>
In FIG. 1, the circuit diagram of the LED lamp 1 of the 1st Embodiment of this invention is shown. The LED lamp 1 is supplied with the input voltage Vin from the power supply device 2 through the input terminals T1 and T2. The LED lamp 1 is an LED lamp for DC input, and it is assumed that an LED power source that is a DC power source is connected as the power supply device 2. In addition, the rated input voltage of the LED lamp 1 is lower than the peak voltage of the commercial power supply. The LED lamp 1 includes a full-wave rectifier circuit 10, an LED array 20, a switch circuit 30, a voltage detection circuit 40, and a control circuit 50.

  The full-wave rectifier circuit 10 is composed of a diode bridge and full-wave rectifies the input voltage Vin from the power supply device 2. Therefore, the LED lamp 1 has the input terminal T2 / T1 even if the LED power supply is connected in any polarity (that is, even when the positive / negative polarity of the LED power supply is connected to the input terminal T1 / T2, respectively). In this case, the so-called polarity-free configuration is also possible. A portion having the same potential as the low potential output terminal of the full-wave rectifier circuit 10 is referred to as a ground G, and a portion having the same potential as the high potential output terminal is referred to as a high potential wiring H.

  The LED array 20 includes a series circuit or a series-parallel circuit of LED elements, and an anode end thereof is connected to the high potential side wiring H. The forward voltage of the LED array 20 is the total forward voltage of the LED elements constituting the LED array 20.

  The switch circuit 30 includes a switch element 31, a resistor 32, and a capacitor 33. The switch element 31 is composed of a MOSFET (hereinafter referred to as “FET 31”). The drain is connected to the cathode end of the LED array 20 and the source is connected to the ground G. The gate is connected to the control circuit 50, and the resistor 32 and the capacitor 33 are connected between the gate and the source. On / off of the FET 31 is controlled by the control circuit 50.

  The voltage detection circuit 40 includes resistors 41, 43, 44 and 45 and diodes 43 and 46. The voltage of the input terminal T1 with respect to the ground G is divided by the resistors 41 and 42, and this divided voltage is rectified by the diode 43. Similarly, the voltage of the input terminal T 2 with respect to the ground G is divided by the resistors 44 and 45, and this divided voltage is rectified by the diode 46. Therefore, a voltage obtained by dividing and full-wave rectifying the input voltage Vin is generated at the common cathode of the diodes 43 and 46. A voltage generated at the common cathode of the diodes 43 and 46 is referred to as a detection voltage Vd. The resistors 41 and 42 and the resistors 44 and 45 have the same voltage dividing ratio r.

  The control circuit 50 includes an IC 51, a resistor 52, a Zener diode 53, a resistor 54, a capacitor 55, a transistor 56, and resistors 57 to 59. The IC 51 is a microcomputer or the like and has at least terminals P1 to P4. The terminal P 1 is a power supply terminal, and a control voltage is supplied from the high potential side wiring H through the resistor 52. A Zener diode 53, a resistor 54, and a capacitor 55 are connected between the terminal P1 and the ground G. The control voltage is made constant to the Zener voltage of the Zener diode 53 and is stabilized by the capacitor 55. The terminal P2 is an input terminal, to which the common cathode of the diodes 43 and 46 is connected and the detection voltage Vd is input. The terminal P3 is an output terminal and is connected to the base of the transistor 56 via the resistor 57. The emitter of the transistor 56 is connected to the ground G, and a resistor 58 is connected between the base and the emitter. The collector of the transistor 56 is connected to the high potential side wiring H via the resistor 59 and to the gate of the FET 31. The terminal P4 is a ground terminal and is connected to the ground G.

  That is, in the IC 51, a control voltage is supplied from the terminal P1, a detection voltage Vd is input from the terminal P2, and a base signal is output from the terminal P3 to the transistor 56 based on processing according to the detection voltage Vd. As an outline, the IC 51 determines whether or not the detection voltage Vd is a rectified waveform of an AC voltage (that is, whether or not the input voltage Vin is an AC voltage). When the IC 51 determines that the detection voltage Vd is a rectified waveform of an AC voltage, the transistor 56 is turned on and the FET 31 is turned off (that is, the voltage between the high potential side wiring H and the ground G is the LED array). 20). In other cases, the IC 51 turns off the transistor 56 and turns on the FET 31 to light the LED array 20.

  When the IC 51 detects a waveform portion where the detection voltage Vd is equal to or lower than the predetermined threshold value V1, the IC 51 determines that the input voltage Vin is an AC voltage and turns on the transistor 56 (that is, turns off the FET 31). This threshold value V1 is a value less than the lower limit value of the voltage range Vf obtained by multiplying the forward voltage range VF that gives the rated current to the LED array 20 by the voltage dividing ratio r. Hereinafter, the operation in which the IC 51 turns on the transistor 56, that is, the operation in which the control circuit 50 turns off the FET 31 is referred to as a protection operation.

  For example, the IC 51 may perform the protection operation when the detection voltage Vd becomes equal to or less than the threshold value V1 or when the period during which the detection voltage Vd becomes equal to or less than the threshold value V1 continues for a predetermined time or more. Further, the IC 51 may detect a falling edge in which the detection voltage Vd is lower than the threshold value V1, and may perform the protection operation when the falling edge is detected a predetermined number of times or more. Alternatively, the IC 51 detects a rising edge where the detection voltage Vd exceeds the threshold value V1, and performs a protection operation when a rising edge (excluding the rising edge when the input voltage Vin is input) is detected a predetermined number of times or more. It may be. Further, the IC 51 may execute the above-described protection operation based on the logical sum or logical product of the respective detection results.

The operation of the LED lamp 1 will be described with reference to FIGS. 2A to 2C.
FIG. 2A shows the detection voltage Vd and the operation of the FET 31 associated therewith when the power supply device 2 is an LED power supply. The power supply for LED used in the present disclosure is a power supply device suitable for the LED lamp 1, and supplies the input voltage Vin within the forward voltage range VF to the terminals T1-T2. The horizontal axis of each diagram showing the operation in the present disclosure is time, and each waveform is omitted or exaggerated for convenience of explanation.

  As shown in FIG. 2A, when the power supply apparatus 2 is an LED power supply, the detection voltage Vd is a substantially constant voltage within the voltage range Vf, and does not fall below the threshold value V1. Therefore, the IC 51 maintains the transistor 56 in the off state and maintains the FET 31 in the on state. Thereby, the LED array 20 continues to be lit.

  FIG. 2B shows the detected voltage Vd and the operation of the FET 31 associated therewith when the power supply device 2 is a magnetic ballast. The magnetic ballast used in the present disclosure is an AC power supply device that is incompatible with the LED lamp 1, and supplies a sine wave voltage substantially equal to the commercial power supply voltage to the terminals T1-T2 as the input voltage Vin. To do. As a result, the LED array 20 is intermittently lit at a frequency twice that of the power supply frequency (that is, 100 Hz or 120 Hz).

  As shown in FIG. 2B, the detection voltage Vd is a full-wave pulsating waveform having a frequency twice the power supply frequency, is below the voltage range Vf before and after the zero crossing, and exceeds the voltage range Vf before and after the peak. If the FET 31 is fixed in the ON state, a voltage that can exceed the forward voltage range VF in the LED array 20 near the peak of the full-wave pulsating voltage (for example, about 140 V when the power supply voltage is 100 Vac, In the case of 200 Vac, about 280 V) is applied, and the continuation of this overvoltage input state will lead to failure or shortening of the life of the LED array 20. On the other hand, in the present embodiment, the IC 51 stops the overvoltage state in the LED array 20 by the detection and determination processing described above. Thereby, the intermittent lighting of the LED array 20 is stopped.

  In the example of FIG. 2B, for convenience of explanation, it is assumed that detection and determination processing in the IC 51 is started at time ts. In this example, the IC 51 turns the transistor 56 on and the FET 31 off at time td when the detection voltage Vd falls below the threshold value V1. Note that the time td at which the FET 31 is turned on may vary depending on the applied process. For example, when detection of a plurality of falling edges or rising edges is used, the time td is a time later than that illustrated.

  FIG. 2C shows the detected voltage Vd and the operation of the FET 31 associated therewith when the power supply device 2 is a high-pressure discharge lamp ballast. The ballast for the high-pressure discharge lamp is an AC power supply device that is incompatible with the LED lamp 1, and supplies a square wave voltage of several hundred Hz to the terminals T1-T2 as the input voltage Vin. Therefore, the voltage applied to the LED array 20 is substantially a constant voltage (except when polarity is reversed). When the input voltage Vin is greater than or equal to the forward voltage range VF, the LED array 20 is lit and the input voltage Vin is When it is less than the forward voltage range VF, the LED array 20 is not lit. Further, the detection voltage Vd also has a substantially constant voltage waveform, but an edge Vi at the time of polarity inversion appears at a frequency twice the rectangular wave frequency. In the example of FIG. 2C, the detection and determination processing in the IC 51 is started at time ts.

  In this example, the IC 51 can detect the edge Vi at the time of polarity inversion as a falling edge or a rising edge and perform the above-described protection operation. That is, in this example, the IC 51 turns on the transistor 56 and turns off the FET 31 at time td when the edge Vi occurs. As a result, the LED array 20 is turned off (if turned on).

  As described above, according to the above processing, the detection voltage Vd when the power supply device 2 is the LED power supply does not become the threshold value V1 or less, and the protection operation is not activated. On the other hand, since the detected voltage Vd when the power supply device 2 is a magnetic ballast and a high-pressure discharge lamp ballast has a waveform portion that is equal to or lower than the threshold value V1, a protection operation is performed. In addition, when the peak Vp of the output voltage of the ballast for the high-pressure discharge lamp is lower than the threshold value V1, the protection operation is not executed. In other words, in such a case, a failure of the LED array 20 is not assumed (because the LED array 20 is not lit), and thus no protection operation is necessary.

  As described above, the LED lamp 1 for DC input according to the present embodiment includes the full-wave rectifier circuit 10 for full-wave rectification of the input voltage Vin, the LED array 20 and the FET 31 to which the output voltage of the full-wave rectifier circuit 10 is applied. A series detection circuit, a voltage detection circuit 40 that divides and rectifies the input voltage Vin and outputs a detection voltage Vd, and maintains the FET 31 in an OFF state when it is determined that the detection voltage Vd is a rectified waveform of an AC voltage. The control circuit 50 configured as described above is provided. That is, when the input voltage Vin is an AC voltage, the FET 31 is turned off, and the current path between the full-wave rectifier circuit 10 and the LED array 20 is opened. Therefore, the overvoltage from the incompatible AC power supply device to the LED array 20 is reduced. Application is stopped. Therefore, the LED lamp 1 for direct current input that can prevent the failure or shortening of the life of the LED array 20 when an incompatible AC power supply device is connected is realized.

  In particular, in the present embodiment, the voltage detection circuit 40 includes a voltage dividing rectifier circuit (41 to 46) that divides the input voltage Vin by the voltage dividing ratio r and performs full-wave rectification to output the detection voltage Vd. Then, a threshold value V1 less than the lower limit value of the voltage range Vf obtained by multiplying the forward voltage range VF that gives the rated current to the LED array 20 by the voltage dividing ratio r is defined, and the control circuit 50 causes the detection voltage Vd to be equal to or less than the threshold value V1. When the waveform portion is detected, the FET 31 is configured to be kept off. Thereby, the low-cost LED lamp 1 using the control circuit 50 having a simple processing configuration is realized.

<Modification of First Embodiment>
In the above, the configuration in which the voltage detection circuit 40 divides and full-wave rectifies the input voltage Vin is shown, but in this modification, the configuration in which the voltage detection circuit 40 divides and half-wave rectifies the input voltage Vin is shown. .

  In FIG. 3, the circuit diagram of the LED lamp 1 of this modification is shown. In the present modification, the same reference numerals are given to the same configurations or values as those in the above-described embodiment, and the overlapping description is omitted. In this modification, the configuration of the voltage detection circuit 40 and the processing in the IC 51 are different from those in the above embodiment.

  The voltage detection circuit 40 includes resistors 41 and 42 and a diode 43 connected to the input terminal T1, and the input terminal Vin of the IC 51 to which the cathode of the diode 43 is connected is divided and half-wave rectified. A waveform detection voltage Vd is input.

  The IC 51 performs a protection operation when the detection voltage Vd is detected within the predetermined voltage range Va. The voltage range Va is a predetermined voltage range that is lower than the voltage range Vf and higher than zero. For example, the IC 51 may perform the protection operation when the detection voltage Vd enters the predetermined voltage range Va, or the protection operation when the number of times the detection voltage Vd enters the predetermined voltage range Va reaches a predetermined number. May be executed.

The operation of the LED lamp 1 will be described with reference to FIGS. 4A to 4C.
4A shows, from the top, the detection voltage Vd when the power supply 2 is an LED power supply and the positive terminal is connected to the input terminal T1, and the power supply 2 is an LED power supply and the negative terminal is connected to the input terminal T1. The detection voltage Vd and the operation of the FET 31 are shown. As shown in FIG. 4A, when the output voltage on the positive side of the LED power supply is detected, the detection voltage Vd is a substantially constant voltage within the voltage range Vf. On the other hand, when the output voltage on the negative side of the LED power supply is detected, the detection voltage Vd is zero and constant. Therefore, in any case, since the detection voltage Vd is not included in the voltage range Va, the IC 51 maintains the transistor 56 in the off state and maintains the FET 31 in the on state. Thereby, the LED array 20 continues to be lit.

  FIG. 4B shows the detected voltage Vd and the operation of the FET 31 associated therewith when the power supply device 2 is a magnetic ballast. As shown in FIG. 4B, when the power supply device 2 is a magnetic ballast, the detection voltage Vd has a half-wave pulsating waveform having a frequency equal to the power supply frequency (that is, 50 Hz or 60 Hz). In the example of FIG. 4B, for convenience of explanation, it is assumed that detection and determination processing in the IC 51 is started at time ts. In this example, the IC 51 turns the transistor 56 on and the FET 31 off at time td when the detection voltage Vd enters the voltage range Va. Thereby, the intermittent lighting of the LED array 20 is stopped.

  FIG. 4C shows the detection voltage Vd and the operation of the FET 31 associated therewith when the power supply device 2 is a high-pressure discharge lamp ballast. As described above, since the high-pressure discharge lamp ballast outputs a rectangular wave voltage of several hundred Hz, the detection voltage Vd, which is a half-wave rectified waveform, also becomes a rectangular wave having the same frequency. Also in the example of FIG. 4C, it is assumed that the detection and determination processing in the IC 51 is started at time ts. In this example, the IC 51 turns the transistor 56 on and the FET 31 off at time td when the voltage polarity reverses from positive to negative (that is, enters the voltage range Va). As a result, the LED array 20 is turned off (if turned on).

  Thus, according to the above processing, the detection voltage Vd when the power supply device 2 is the LED power supply is not included in the predetermined voltage range Va, and the protection operation is not activated. On the other hand, since the detected voltage Vd when the power supply device 2 is a magnetic ballast or a high-pressure discharge lamp ballast has a waveform portion included in the predetermined voltage range Va, a protection operation is performed.

  As described above, in the present modification, the voltage detection circuit 40 includes the voltage dividing rectifier circuit (41 to 43) that divides the input voltage Vin by the voltage dividing ratio r and rectifies the wave by half wave to output the detected voltage Vd. A predetermined voltage range Va that is less than the voltage range Vf obtained by multiplying the forward voltage range VF that gives the rated current to the LED array 20 by the voltage dividing ratio r and that is higher than zero is defined, and the control circuit 50 determines the waveform of the detection voltage Vd. Is detected in a predetermined voltage range Va, the FET 31 is configured to be maintained in an off state. Thereby, the low-cost LED lamp 1 using the voltage detection circuit 40 having a simple half-wave rectification configuration is realized.

<Second Embodiment>
In the first embodiment, the configuration in which the protection operation is performed when the detection voltage Vd has a waveform portion that is less than or equal to the threshold value V1 that is less than the lower limit value of the voltage range Vf has been described. A configuration is shown in which a protection operation is performed when Vd has a waveform portion that exceeds a threshold value equal to or greater than the upper limit value of the voltage range Vf. The circuit configuration of the LED lamp 1 of the present embodiment is the same as the circuit configuration of the LED lamp 1 of the first embodiment (FIG. 1).

  When the IC 51 detects a waveform portion in which the detection voltage Vd exceeds the threshold value V2, the IC 51 turns on the transistor 56 and turns off the FET 31, thereby performing a protection operation. The threshold value V2 is a value equal to or greater than the upper limit value of the voltage range Vf obtained by multiplying the forward voltage range VF that gives the rated current to the LED array 20 by the voltage dividing ratio r. For example, the IC 51 can perform the protection operation when the detection voltage Vd exceeds the threshold value V2 or when a period in which the detection voltage Vd exceeds the threshold value V2 continues for a predetermined time or more.

The operation of the LED lamp 1 will be described with reference to FIGS. 5A and 5B.
FIG. 5A shows the detection voltage Vd and the operation of the FET 31 associated therewith when the power supply device 2 is an LED power supply. As shown in FIG. 5A, when the power supply device 2 is an LED power supply, the detection voltage Vd is a substantially constant voltage within the voltage range Vf and does not exceed the threshold value V2. Therefore, the IC 51 maintains the transistor 56 in the off state and maintains the FET 31 in the on state. Thereby, the LED array 20 continues to be lit.

  FIG. 5B shows the detected voltage Vd and the operation of the FET 31 associated therewith when the power supply device 2 is a magnetic ballast. As shown in FIG. 5B, when the power supply device 2 is a magnetic ballast, the detection voltage Vd becomes a full-wave pulsating waveform having a frequency twice the power supply frequency, and exceeds the threshold value V2 near the peak. The IC 51 turns on the transistor 56 and turns off the FET 31 at time td when the detection voltage Vd exceeds the threshold value V2. Thereby, the intermittent lighting of the LED array 20 is stopped.

  Similarly, when the power supply device 2 is a high-pressure discharge lamp ballast, the IC 51 turns on the transistor 56 and turns off the FET 31 when the detection voltage Vd exceeds the threshold value V2. As a result, the LED array 20 is turned off.

  According to the above processing, the detection voltage Vd when the power supply device 2 is an LED power supply does not exceed the threshold value V2, and the protection operation is not activated. On the other hand, since the detected voltage Vd when the power supply device 2 is a magnetic ballast or a high-pressure discharge lamp ballast has a waveform portion exceeding the threshold value V2, a protection operation is performed. However, when the peak Vp of the output voltage of the high-pressure discharge lamp ballast is equal to or lower than the threshold value V2, the protection operation is not activated.

  As a modification, the voltage detection circuit 40 may have a half-wave rectification configuration (see FIG. 3) including resistors 41 and 42 and a diode 43. Even in this case, the IC 51 can perform the protection operation by the same detection and determination processing as described above for the case where the voltage detection circuit 40 has the full-wave rectification configuration. However, in the case of the half-wave rectification configuration, since the period of the detected pulsating voltage is doubled compared to the full-wave rectification configuration, the activation of the protection operation can be delayed.

  As described above, in the LED lamp 1 of the present embodiment, the voltage detection circuit 40 divides the input voltage Vin by the voltage division ratio r and outputs the detection voltage Vd by full-wave rectification or half-wave rectification. (41-46 or 41-43). Then, a threshold value V2 equal to or higher than the upper limit value of the voltage range Vf obtained by multiplying the forward voltage range VF that gives the rated current to the LED array 20 by the voltage dividing ratio r is defined, and the control circuit 50 has a waveform in which the detection voltage Vd exceeds the threshold value V2. The FET 31 is configured to be kept off when the portion is detected. Thereby, the low-cost LED lamp 1 using the control circuit 50 having a simple processing configuration is realized with the effect of preventing the failure and shortening of the life of the LED array 20 described in the first embodiment.

<Third Embodiment>
In the first or second embodiment, the configuration in which the protection operation is performed when the input voltage Vin is determined to be an AC voltage is shown, but in the present embodiment, the notification is performed along with the execution of the protection operation. The configuration is shown.

  FIG. 6 shows a circuit diagram of the LED lamp 1 of the present embodiment. In this embodiment, the same code | symbol is attached | subjected to the structure similar to 1st or 2nd embodiment, and the overlapping description is abbreviate | omitted. The LED lamp 1 of this embodiment is different from the LED lamp 1 of the first and second embodiments in that it includes a notification circuit 60.

  The notification circuit 60 includes a resistor 61, a warning LED 62 and a transistor 63 in series, and resistors 64 and 65. The series circuit is connected between a terminal P1 (power supply terminal) and the ground G. It is assumed that the warning LED 62 is disposed at a position that can be visually recognized by the user in the LED lamp 1. Further, it is desirable that the light emission color of the warning LED 62 is different from the light emission color of the LED array 20. The base of the transistor 63 is connected to the terminal P3 (output terminal) via the resistor 64, and the resistor 65 is connected between the base and the emitter.

  With the above circuit configuration, the transistor 63 operates with the same logic as the transistor 56. Accordingly, during normal lighting when the FET 31 is on, the transistor 63 is off and the warning LED 62 is turned off. On the other hand, during the protection operation in which the FET 31 is in the off state, the transistor 63 is in the on state, and the warning LED 62 is lit using the control voltage of the control circuit 50 (IC 51) as a voltage source. The voltage source of the warning LED 62 is not limited to the control voltage, but is an output voltage of a separate constant voltage circuit (for example, a circuit having the same configuration as the resistor 52, the Zener diode 53, the resistor 54, and the capacitor 55). Also good.

  The detection and determination processing related to the detection voltage Vd in the IC 51 may be any processing described in the first or second embodiment. In this connection, FIG. 6 shows a full-wave rectification configuration as the voltage detection circuit 40, but the voltage detection circuit 40 may have a half-wave rectification configuration (see FIG. 3) as a modification. When the operation examples shown in FIGS. 2B, 2C, 4B, 4C, and 5B are applied, the warning LED 62 is lit after time td.

  As described above, the LED lamp 1 of the present embodiment further includes the warning LED 62 and the transistor 63 (informing circuit 60) connected in series to a predetermined voltage source. When the control circuit 50 (IC51) turns the FET 31 on, the transistor 63 is turned off and the warning LED 62 is turned off. When the FET 31 is turned off, the transistor 63 is turned on and the warning LED 62 is turned on. Configured to let As a result, in addition to the effects described above in the first or second embodiment, the user recognizes by turning on the warning LED 62 that the turn-off of the LED array 20 is caused by an incompatible AC power supply device being connected. It is possible to urge the correct use of the LED lamp 1.

<Fourth Embodiment>
In the first to third embodiments, the configuration in which the protection operation is performed after the suitability of the input voltage Vin is determined is shown. However, in the present embodiment, the protection operation is performed with the fluctuation of the input voltage Vin. Indicates. The circuit configuration of the LED lamp 1 of the present embodiment is the same as the circuit configuration of the LED lamp 1 of the first embodiment (FIG. 1). The lower limit value and the upper limit value of the voltage range Vf obtained by multiplying the forward voltage range VF that gives the rated current to the LED array 20 by the voltage dividing ratio r are referred to as V3 and V4, respectively.

  In the present embodiment, the IC 51 turns on the transistor 56 and turns off the FET 31 during a period when the detection voltage Vd exceeds the upper limit value V4. Therefore, the IC 51 may be a comparator. In this case, the terminal P1 corresponds to the power supply terminal of the comparator, and the terminal P2 corresponds to the non-inverting input terminal (+) of the comparator. A circuit for dividing the control voltage of the terminal P1 is provided, and a divided value corresponding to the upper limit value V4 is input to the inverting input terminal (−) of the comparator.

The operation of the LED lamp 1 will be described with reference to FIGS. 7A and 7B.
FIG. 7A shows the detection voltage Vd and the accompanying operation of the FET 31 when the power supply 2 is an LED power supply. As shown in FIG. 7A, when the power supply device 2 is an LED power supply, the detection voltage Vd is a substantially constant voltage within the voltage range Vf and does not exceed the upper limit value V4. Therefore, the IC 51 maintains the transistor 56 in the off state and maintains the FET 31 in the on state. Thereby, lighting of the LED array 20 continues.

  FIG. 7B shows the detected voltage Vd and the operation of the FET 31 associated therewith when the power supply device 2 is a magnetic ballast. As shown in FIG. 7B, when the power supply device 2 is a magnetic ballast, the detection voltage Vd is a full-wave pulsating waveform having a frequency twice the power supply frequency. Here, in the unit cycles t0 to t5, the detection voltage Vd exceeds the lower limit value V3 at time t1, exceeds the upper limit value V4 at time t2, falls below the upper limit value V4 at time t3, and falls below the lower limit value V3 at time t4. .

The IC 51 turns off the transistor 56 and turns on the FET 31 during the periods t0 to t2 and the periods t3 to t5 where the detection voltage Vd is equal to or lower than the upper limit value V4. The transistor 56 is turned on and the FET 31 is turned off.
That is, the protection operation is executed in the period t2 to t3 in each voltage cycle. Thereby, application of overvoltage to the LED array 20 in the period t2 to t3 is prevented. The LED array 20 is turned off during the periods t0 to t1 and the periods t4 to t5 of each cycle, and is turned on during the periods t1 to t2 and the periods t3 to t4.

  Further, when the power supply device 2 is a high-pressure discharge lamp ballast, when the detection voltage Vd, which is a substantially constant voltage (that is, other than during polarity reversal) exceeds the upper limit value V4, it is substantially always protected. The operation will be executed. On the other hand, when the detection voltage Vd is not less than the lower limit value V3 and not more than the upper limit value V4, the protection operation is not performed and the LED array 20 is turned on, and when the detection voltage Vd is less than the lower limit value V3, the LED array 20 is turned off. (Protection operation is not executed).

  As described above, the LED lamp 1 of the present embodiment includes the full-wave rectifier circuit 10 that performs full-wave rectification on the input voltage Vin, and the series circuit of the LED array 20 and the FET 31 to which the output voltage of the full-wave rectifier circuit 10 is applied. A voltage detection circuit 40 that divides the input voltage Vin by the voltage division ratio r and outputs the detection voltage Vd by full-wave rectification, and a voltage obtained by multiplying the forward voltage range VF that gives the rated current to the LED array 20 by the voltage division ratio r An upper limit value V4 of the range Vf is defined, and a control circuit 50 configured to turn off the FET 31 during a period in which the detection voltage Vd exceeds the upper limit value V4 is provided. That is, when the input voltage Vin is a high peak AC voltage, the FET 31 is turned off in the vicinity of the peak, and the current path between the full-wave rectifier circuit 10 and the LED array 20 is opened. Application of overvoltage from the device to the LED array 20 is prevented. Therefore, the LED lamp 1 for DC input that can prevent the failure or shortening of the life of the LED array 20 even when an incompatible AC power supply device is connected is realized.

<Modification>
Although preferred embodiments of the present invention have been described above, the present invention can be modified into various modes as shown below, for example.

(1) Modification of Voltage Detection Circuit 40 In each of the above embodiments, the voltage detection circuit 40 is provided as an independent circuit. However, the full-wave rectifier circuit 10 may constitute a part of the voltage detection circuit 40. For example, a configuration in which a voltage dividing resistor is connected between the output terminals of the full-wave rectifier circuit 10 and the divided voltage value is input to the terminal P2 of the IC 51 may be employed. Further, in each of the above embodiments, the configuration in which the input voltage Vin divided by the voltage dividing resistors 41, 42, 44, and 45 is rectified by the diodes 43 and 46 is shown. As a result, the withstand voltage of the diodes 43 and 46 can be reduced. On the other hand, a configuration in which the input voltage Vin rectified by the diode is divided by a voltage dividing resistor may be employed. In this case, the breakdown voltage of the voltage dividing resistor can be reduced.

(2) Modification of control circuit 50 etc. In each of the above embodiments, the IC 51 operates the FET 31 via the transistor 56. However, when the IC 51 can directly operate the FET 31, the terminal P 3 is connected to the FET 31. It is good also as a structure connected to this gate. In this case, the output logic of the terminal P3 is opposite to the output logic in the above embodiments. In the above embodiments, the transistors 56 and 63 are shown as bipolar transistors, but one or both of them may be MOSFETs. In this case, the base corresponds to the gate, the collector corresponds to the drain, and the emitter corresponds to the source.

DESCRIPTION OF SYMBOLS 1 LED lamp 10 Full wave rectifier circuit 20 LED array 30 Switch circuit 31 Switch element (FET)
40 Voltage detection circuit 50 Control circuit 60 Notification circuit 62 Warning LED
63 transistors

Claims (6)

An LED lamp for direct current input,
A full-wave rectifier circuit for full-wave rectification of the input voltage;
A series circuit of an LED array and a switch element to which an output voltage of the full-wave rectifier circuit is applied;
A voltage detection circuit that divides and rectifies the input voltage and outputs a detection voltage;
An LED lamp comprising: a control circuit configured to maintain the switch element in an OFF state when it is determined that the detected voltage is a rectified waveform of an AC voltage. The voltage detection circuit comprises a voltage division rectification circuit that divides the input voltage at a predetermined voltage division ratio and performs full-wave rectification to output the detection voltage,
A threshold value less than a lower limit value of a voltage range obtained by multiplying the voltage division ratio by a forward voltage range that gives a rated current to the LED array is defined,
The LED lamp according to claim 1, wherein the control circuit is configured to maintain the switch element in an OFF state when detecting a waveform portion where the detection voltage is equal to or less than the threshold. The voltage detection circuit comprises a voltage division rectification circuit that divides the input voltage at a predetermined voltage division ratio and half-wave rectifies and outputs the detection voltage,
A predetermined voltage range that is less than a lower limit value of a voltage range obtained by multiplying the voltage division ratio by a forward voltage range that gives a rated current to the LED array and that is higher than zero is defined.
The LED lamp according to claim 1, wherein the control circuit is configured to maintain the switch element in an OFF state when the detection voltage is detected in the predetermined voltage range. The voltage detection circuit comprises a voltage division rectification circuit that divides the input voltage at a predetermined voltage division ratio and outputs the detection voltage by full-wave rectification or half-wave rectification,
A threshold value is defined that is equal to or higher than the upper limit value of the voltage range obtained by multiplying the voltage division ratio by a forward voltage range that gives a rated current to the LED array,
The LED lamp according to claim 1, wherein the control circuit is configured to maintain the switch element in an OFF state when detecting a waveform portion in which the detection voltage exceeds the second voltage. A warning LED and a transistor connected in series to a predetermined voltage source;
The control circuit turns off the warning LED by turning off the transistor when turning on the switch element, and turns off the warning LED by turning off the warning LED when turning off the switch element. The LED lamp according to claim 1, wherein the LED lamp is configured to be lit. An LED lamp for direct current input,
A full-wave rectifier circuit for full-wave rectification of the input voltage;
A series circuit of an LED array and a switch element to which an output voltage of the full-wave rectifier circuit is applied;
A voltage detection circuit that divides the input voltage at a predetermined voltage division ratio and outputs a detection voltage by full-wave rectification;
An upper limit value of a voltage range obtained by multiplying the voltage division ratio by a forward voltage range giving a rated current to the LED array is defined, and the switch element is turned off during a period when the detected voltage exceeds the upper limit value. LED lamp provided with a control circuit.

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